Some medical procedures, require implanted devices. Hemodialysis, for instance, requires vascular access (that is, access to a patient's vascular system, including veins and arteries). In some cases, vascular access is required over long periods of time and for repeat medical procedures. In such instances, an implant or graft can be placed in the patient to allow for vascular access. One example implant is an arteriovenous (AV) graft, which is a biocompatible tube that links a patient's artery and vein. The tube has access points for access from outside of the patient's body. However, the AV graft is constantly open, and thus constantly and unnaturally diverts blood flow between the patient's artery and vein and vice versa, which can cause complications.